<p>Wireless communications can be affected by high-speed mobility environments, potentially affecting the user experience. For example, the deployment of a dense cluster of LEO satellite-based 5G base stations to serve masses of users with real-time services might experience communication interruption due to frequent handovers because of high mobility and long distance. Also, the integration of heterogeneous networks to fulfill user demands brings out different scenarios of handovers to deal with. Aiming to reduce the handover latency of legacy handover schemes, a fast handover scheme based on a pre-registration mechanism is proposed. The paper proposes a dwell-time estimation-based handover scheme that computes the serving time of a base station and performs a-priori registration of User Equipment (UE) at its target base station. A path duplication approach is introduced to reduce handover latency and the probability of handover failure. A network scenario is considered where the UE has the capability to connect to terrestrial or satellite networks depending upon the signal quality. This gives rise to handover scenarios, such as inter-satellite and integrated satellite-terrestrial handovers. The paper analytically models each of the handover scenarios followed by its performance evaluation in terms of handover delay and probability of handover failure for variable processing delay of a base station (gNB) as well as for variable UE velocity. The performance comparison with the legacy handover shows a reduction of handover latency by 28.22% and 36.23% in each of the inter-satellite and integrated satellite-terrestrial handover scenarios, respectively.</p>